1. Field of the Invention
The present invention relates generally to a method for forming a semiconductor device, and more particularly to a method for forming a multi-layered structure using a thermally conductible stage. The present invention also relates to methods for forming a capacitor and a gate insulation film by employing the multi-layered structure.
2. Description of the Related Art
Manufacturing technology for semiconductor devices has been developed which enhances integration density, reliability, response speed, etc. Deposition process are processes use in manufacturing semiconductor devices. Thus, it is especially important to improve the deposition processes so that the integration density of the semiconductor devices can be increased. The deposition processes utilized to form thin films on a semiconductor substrate include a process to form a gate insulation film and another process to form a capacitor dielectric film. Both the gate insulation film and the dielectric film of a capacitor should have high dielectric constants in order to perform at a required design standard. A method for forming a gate insulation film or the dielectric film of a capacitor using a material having a high dielectric constant is disclosed in U.S. Pat. No. 6,066,525 (issued to Liu et al.) and U.S. Pat. No. 6,320,238 (issued to Kizilyalli et al.).
A thin film having a high dielectric constant, which can include a metal oxide, has previously been used to form the gate insulation film or the dielectric film of a capacitor. More recently, the gate insulation film the dielectric film of the capacitor has been formed using a multi-layered structure in which more than two thin films, composed of metal oxides, are included. For example, U.S. Pat. No. 6,479,403 (issued to Tsei et al.) provides a multi-layered structure including two thin films.
FIG. 1 is a schematic plan view illustrating a conventional deposition apparatus for forming the multi-layered structure of a semiconductor device.
Referring to FIG. 1, a deposition apparatus 1 includes a first and second chamber 11 and 13 that are separated from each other. The deposition apparatus 1 further includes a transfer chamber 15 for transferring a semiconductor substrate 17 between the first and second chambers 11 and 13. Therefore, the transfer chamber 15 connects the first chamber 11 to the second chamber 13. A multi-layered structure including two thin films is formed on the semiconductor substrate 17 using the deposition apparatus 1. For example, the multi-layered structure including an aluminum oxide (Al2O3) thin film and a titanium oxide (TiO2) thin film can be formed on the semiconductor substrate 17 with the deposition apparatus 1.
Now, a method for forming the multi-layered structure on the semiconductor substrate using the deposition apparatus 1 will be described.
The semiconductor substrate 17 is loaded into the first chamber 11 from the transfer chamber 15 along the direction of A. An aluminum oxide thin film is formed on the semiconductor substrate 17 in the first chamber 11. The aluminum oxide thin film is formed on the semiconductor substrate 17 at a temperature of about 450° C. for about 400 second.
After the aluminum oxide thin film is formed on the semiconductor substrate 17, the semiconductor substrate 17 is transferred from the first chamber 11 to the transfer chamber 15 along the direction B. Then, the semiconductor substrate 17 is loaded into the second chamber 13 from the transfer chamber 15 in the direction C. A titanium oxide thin film is formed on the aluminum oxide thin film in the second chamber 13. In this case, the titanium oxide thin film is formed at a temperature of about 350° C. for about 200 seconds. After the titanium oxide thin film is formed on the aluminum oxide thin film, the semiconductor substrate 17 including the thin films is transferred from the second chamber 13 to the transfer chamber 15 in the direction of D. Thus, the multi-layered structure including the aluminum oxide and titanium oxide thin films is formed on the semiconductor substrate 17.
As described above, the gate insulation film or the dielectric film of the capacitor including the above-mentioned multi-layered structure, in which two thin films having different deposition characteristics are included, is formed on the semiconductor substrate from two separated chambers without vacuum break during the formations of the thin films. However, the productivity and the operation efficiency of the deposition apparatus may be low because two thins films are independently formed in the separated chambers. Namely, the second chamber 13 is empty for more than 200 second while the aluminum oxide thin film is formed in the first chamber. This is because the aluminum oxide thin film is formed in the first chamber 11 for about 400 second while the formation of the titanium oxide thin film in the second chamber 13 takes only about 200 second. Thus, the above-described process lowers the productivity and the operation efficiency of the deposition apparatus. Particularly, the productivity and the operation efficiency of the deposition apparatus may be seriously decreased during the formations of the thin films when there are significant time differences between the formations of the thin films. In addition, the aluminum oxide thin film is formed at a temperature of about 450° C. while the titanium oxide thin film is formed at a temperature of about 350° C. Therefore, it may be difficult to further reduce the productivity of the deposition apparatus if the temperature of the semiconductor substrate cannot be rapidly changed during the formations of the two thin films. At best with the conventional deposition apparatus, the temperature of the semiconductor substrate is merely changed by several centigrade degrees per minute. Thus, the large variation in temperature of the film forming processes requires even more wasted time, again lowering the efficiency of production. Additionally, contaminants such as particles in the transfer chamber may be absorbed on the semiconductor substrate because the semiconductor substrate must be frequently transferred from one chamber to another chamber during the formation of the multi-layered structure.
Nowadays, a method has been developed for forming a first thin film and a second thin film on a semiconductor substrate in-situ in one chamber. That is, the first and second thin films are formed at different temperatures in accordance with the variation of the temperature of a heating member like a heater that heats a semiconductor substrate. However, the variation rate of the temperature of the semiconductor substrate is merely changed by several centigrade per minute (° C./min) when the semiconductor substrate is heated using the heating member. As a result, there is still wasted time for the varying the temperature of the semiconductor substrate between film formations that requires several minutes when the temperature of the semiconductor substrate must be changed by a relatively large amount.
FIG. 2 is a graph showing the variation of the temperature of a substrate during the formation of the multi-layered structure with a conventional heating member. In FIG. 2, the solid line represents the temperature of a heating member, and a phantom (dashed) line indicates the temperature of a semiconductor substrate. A first thin film is formed on the semiconductor substrate for a first time interval I, then the temperature of the semiconductor substrate is changed for a second time interval II, and a second thin film is formed on the first thin film for a third time interval III.
Referring to FIG. 2, the temperature of the semiconductor substrate characteristically depends on the temperature of the heating member. The temperature of the semiconductor substrate is changed from a first temperature T1 to a second temperature T3 according to the variation of the temperature of the heating member from T0 to T2. As a result, the variation in temperature of the semiconductor substrate may demand a significant amount of time when the temperature of the semiconductor substrate is changed using a heating member. Again, the productivity of the deposition apparatus may be deteriorated when the thin films of the multi-layered structure are formed at different temperatures because the time necessary to vary the temperature of the semiconductor substrate can be large.